The Golden Golems in Darkroot Basin and the Duke's Archives will form into a person upon death. It would appear as if these NPC characters were imprisoned inside the Golems for unknown reasons.

The Darkroot Basin Golden Golem will form into the NPC character Dusk of Oolacile upon death. This character is extremely important as she holds the key to accessing Oolacile, the extra world added as part of the Artorias of the Abyss DLC pack.

The second crystal Golem will only appear in the Duke's Archives if you talk to Siegmeyer of Catarina at Firelink Shrine. Upon death this Golem will transform into Sieglinde of Catarina, Siegmeyer's daughter.